Photo sensors arranged in a matrix, and data lines connected with respective columns of the photo sensors are typically arranged in an existing device for recognizing a print, e.g., a fingerprint, etc., to perform a function of recognizing the print. The print is recognized by scanning respective rows of the photo sensors in sequence to read electrical signals generated and transmitted by the respective rows of the photo sensors to their connected data lines. However, all the photo sensors are illuminated by light while the print is being recognized, so that leakage current may be generated in all the photo sensors. The leakage current is noise in all the other photo sensors than a photo sensor being scanned. Therefore, how to alleviate the noise becomes an urgent problem to be solved in this field.